Effect of 5,7-dihydroxytryptamine on serotonergic control of prolactin secretion and behavior in rats.
The intracisternal administration of 5,7-dihydroxytryptamine (5,7-DHT) to rats resulted in a potentiated response to 5-hydroxytryptophan (5-HTP) when the animals were tested 30 days later. The 5-HTP-induced changes include elevation of serum prolactin, decrease in operant responding, and the magnitude of the "serotonin behavioral syndrome" observed after 5-HTP administration. The serotonin concentration in brains of 5,7-DHT-treated animals reached maximum earlier and remained elevated longer than that of controls following administration of 5-HTP. Brain norepinephrine and dopamine concentration were not affected by 5-HTP in either group of animals. The increase in serum prolactin concentration elicited by administration of the serotonergic agonists quipazine or 5-methoxy-N,N-dimethyltryptamine and by the serotonin uptake inhibitor fenfluramine also was potentiated by pretreating rats with 5,7-DHT. These data suggest that both serotonergic receptor supersensitivity and the absence of presynaptic uptake sites contribute to the enhanced responses to 5-HTP occurring in rats previously treated with 5,7-DHT. The findings further demonstrate that both behavioral and hormonal measures can be used to assess the sensitivity of serotonergic receptors and indicate that 5,7-DHT may be useful in evaluating the role of serotonergic neurons in neuroendocrine function.
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology*; D006916:5-Hydroxytryptophan / Q000378:metabolism; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001921:Brain / Q000187:drug effects; D004102:Dihydroxytryptamines / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005277:Fenfluramine / Q000378:metabolism; D008297:Male; D008732:Methoxydimethyltryptamines / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism*; D011814:Quipazine / Q000378:metabolism; D051381:Rats; D011985:Receptors, Serotonin / Q000187:drug effects*; D012701:Serotonin / Q000378:metabolism
D004102:Dihydroxytryptamines; D008732:Methoxydimethyltryptamines; D011985:Receptors, Serotonin; D005277:Fenfluramine; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D011814:Quipazine; D011388:Prolactin; D006916:5-Hydroxytryptophan